Simplified HTML structure.
Content layout is now 10 columns wide with 1 empty column before and
after content. The first column on the left preserves space for the fix
position vertical buttons bar. The right one is empty.
Manage save button classes depending on form pristine/dirty and
valid/invalid states.
Define fix position for hb-btn-bar and hb-menu-bar. Commented presumly
unused CSS.
Added hb-menu-bar class to define fix menu position.